Life cycle analysis of biodiesel and other biofuels : A review

At a time when the use of fossil fuel means increasing energy scarcity and an environmental crisis in the world in which we live, we need green innovations now more than ever. Growing attention has been drawn to the use of biofuels, such as bioethanol and biodiesel, which have gradually come to make up part of the total energy supply. Despite its rapid development, uncertainties about the environmental and ecological aspects of the production and consumption of biofuel still exist. A life cycle analysis (LCA), with deliberate system boundaries and life cycle inventories, has been applied to evaluate two principal functional parameters, the energy efficiency and GHG balance, from the cradle to the grave of different biofuel feedstocks. However, the results of the entire lifetime estimates varied dramatically in production chains, which make it difficult to take a holistic view about energy intake and yields, economic costs and values, environmental impacts and their benefits. Apart from the diversity in system boundaries and life cycle inventories, a variance in terminologies and the limitations of interdisciplinary communication are the main factors that affect the quality of the results. In this paper, various life cycle analysis models are reviewed and evaluated with a special emphasis on two important biofuels, i.e., biodiesel and ethanol.